Method and means for constructing airplane wings, fuselages, and other structures



June 24, 1930. FQKKER 1,765,791

METHOD AND MEANS FOR CONSTRUCTING AIRPLANE WINGS, FUSELAGES, AND OTHER STRUCTURES Original Filed Jan. 29, 1927 A TTORNE Y Patented June 24, 1930 UNITED STATES PATENT OFFICE ANTHONY H. G. FOKKER, OF NEW YORK, N. Y., ASSIGNOB TO EOKKER AIRCRAFT CORPORATION OF AMERICA, A CORPORATION. OF DELAWARE METHOD AND MEANS FOR GONSTRUGTING AIRPLANE WINGS, FUSELAGES, AND OTHER STRUCTURES Application filed January 29, 1927, Serial 1W0. 164,385. Renewed l tay 6, 1930.

The present invention relates generally to the construction or fabrication of structures embodying metal frame members of special or standard shapes, with a covering materlal, such as fabric, connected thereto, as, for example, in the wings and fuselages of airplanes and the like.

While my invention has a wide range of applicability in the construction of varlous structural units, I am electing to confine the present description, more or less, to a specific and important use, in order that the 1nvention may be clearly and concisely described. However, this election, is merely for illustrative purposes and shall not be construed as a limitation of the scope of the in-- vention, as it will be manifest from the nature thereof and the method of practicing the same, that my invention may be utillzed 1n many ways in the production of any structure wherein its employment may be practicable to unite a fabric or like flexible covering material to a rigid frame member, as one of metal. 1

With specific reference to one field of utility for my invention, it is well known that in the construction or fabrication of alrplane wings of many types, a frame work of metal is covered with a treated fabric, which forms the skin or exposed surfaces of the win This covering material, in accordance wit the present practice, is tied or laced to the frame members by a method of sewing which usually comprises passing the lacing strand through the fabric and around the flanges or top and bottom edges of the frame members, the lacing being tied or knotted at each point of connection with the frame members or at such other points as may be desirable or necessary. Obviously, this method of aflixing the fabric to the frame work, at best, is a slow and laborious process and materially increases the cost of production of a fabric covered wing. The same applies to the construction of a fabric covered fuselage, and to other structures wherein fabric is now laced or tied to metal frame members, substantially in the manner above described.

The general object of the present invention is to provide a method and means for connecting or uniting fabric covering material to metal frame members, wherein the complete structure may be more rapidly and economically produced, than is possible with the employment of existing methods and means, with their attendant disadvantages, as heretofore pointed out.

It is also an object of my invention to unite or join the fabric covering of a metal or other rigid frame-work, to the members of the latter, in such a way that repairs and replacements of damaged frame members or of the covering material, may be accomplished with a minimum of expense for labor and materials, thus eflecting a reduction in maintenance costs, as compared to structures assembled in accordance with the methods now followed.

. More specifically, my invention contemplates the provision of a specially constructed or formed frame member to which a fabric or other flexible covering material may be ]oined by lacing in a manner whereby a multiplicity of knots, with the resulting delay in the assembly of the structure, as in existlng methods, is not required, the connection between the fabric and the frame members in accordance with my invention, being firmer and less likely to rupture or breakage.

My invention also comprehends the uniting of a fabric or other flexible covering material to metal frame members which may be of special shapes and designs, or which may be produced from metal tubing or other standard stock.

Other objects and advantages flowing from the practicing of my invention will become manifest as the description proceeds and I would have it clearly understood that I reserve unto myself all rights to the full range of u'ivalents, both in structure and in use, to w ich I may be entitled under my invention in its broadest aspect.

I shall now describe my method as it may be practiced with the means shown in the accompanying drawings, wherein are depicted certain preferred forms of structures for carrying it into effect.

In the drawings: Figure 1 is a side or longitudinal elevation of a rib, such as employed in the fabrication of the frame work of an airplane wing.

Figure 2 is a top plan view of the structure shown in Figure 1, a fragment being broken away. to disclose the cross-section of the rib relative to that of its flange or head.

Figure 3 is an enlarged sectional view, taken on the line 33 of Figure 1.

Figure 4 is an elevation, partly in section, taken on the line 4-4 of Figure 1, looking in the direction of the arrows.

Figure 5 is an enlarged fragmentary perspective of a section of the rib shown'in Figure 1, illustrating the spar or Wing beam station.

Figure 6 is an enlar ed detail, in perspective, of the line 66 of igure 2, and

Figure 7 is a longitudinal section of a part of a frame member of tubin such as may be used in the construction of t e fuselage or an airplane, or in the production of other structures.

Referring now to the drawings in detail, in which like characters of reference are employed to designate similar parts in thesev- .eral views, the ribshown is blanked and formed up from sheet metal, such as duralumin, it being obvious that the'rib may be of' such contour as may be necessary to produce a conventional or other win curve.

In the formation of the ri the metal along the top and bottom edges thereof, is folded or bent over upon itself to produce the beads or flanges 7 and 8, which may be of any crosssectional configuration. Asshown, these beads are annular in shape, the metal forming the upper one 7 being folded in one direction, as to the left of Fi ure 5, while the lower bead is produced by ending the metal in the opposite direction, the inturned edges of each of the beads being spaced from the opposite wall thereof, although they may be interlocked with the latter by means of cooperating tongues and slots, or otherwise. How- .ever, it has been found that a bead of the type shown affords ample strength and rigidity to the rib as a whole, and also has the advantage of economy in production. With the longi tudinal stability obtained by the rolled edges, the web portion 9 of the rib may be cut out or perforated, as at 10, to lighten the structure, without detracting from the ability of the unit to resist compression forces.

At points properly spaced from the ends of the rib, I provide suitable stations or seats for the main and rear spars or wing beams, which are formed by making diagonal incisions in the web and folding or bending the severed portions or sections of the metal outwardly, as clearly shown at 11 and 12 in Figure 5. These spar engaging flanges 11 and 12, are preferably apertured, as at 13, for the reception of suitable bolts or the like, whereby each rib and the cooperating front and rear spars, which extend through the alined openings 14 of the ribs, may be rigidly joined or A connected. While the spar seats are shown rectangular, they may be of any other outline,

by cross-cutting the periphery'of the head to provide a strap 16, and expandin the metal of the wall inwardly on each side t ereof to form the depressions 17 and 18. As will be noted, the strap 16 is provided with a dependent shoulder 19, formed b. the transverse depression 20 in the top sur ace thereof.

Any suitable dies or other means for effecting the formation of the beads or rolled edges and the integral loops or eyes may be employed. One method involves the use of mated dies which traverse the rib longitudinally to form the heads, the loops or eyes being produced by a separate operation.

In the practice of my invention, as in the fabrication of an airplane wing, for example, the assembled spars and ribs, interconnected as previously described, are covered with a treated fabric which is secured to the top and bottom edges of the ribs by means of linen thread, cord or the like, passed through the fabric and the loops or eyes 15. In affixing the fabric to the frame members, the fastenin thread or cord is passed through the fa ric from its outer surface, then through the loop or eye 15 and brought out again through the fabric, the thread being carried along upon the outer surface of the covermg to the location of the next eye or loop, where the operation is repeated, these steps following in sequence until the fabric has been bound to the rib from end to end.

Obviously, this method of connecting the fabric to the ribs by a continuous or unbroken thread or cord passing through the covering material and the eyes or loops alon the edges ofa frame member insures rapi and economical ap lication of the coverin provision of the eyes or loops 15 and t e manner in which the fabric is super osed upon the ribs,- also permits of the amp oyment of suitably prepared wire as an anchoring medium, in lieu of present threads and cords, with the manifest advanta es.

Of course, where it may found necessary or desirable in the use of thread or cord, to knot the same at each loop, this may be readily accomplished, the cord being severed at the knot or carried along to the next loop. Possible rubbing of the cord upon the edges of the strap 16, with resultin fraying and ultimate breaking, is prevente by the mterdepth to supportthe thread out of contact with said edges.

The

F ollowin the lacing or tying of the covering to the frame, strips or tape may be laid over the exposed fastening medium, whether of thread or wire, and cemented to the fabric, thereby adding materially to the finished a pearance of the wing and the security of t e connection between the frame and its cover In fuselage construction, the frame members, in many instances, are, composed of metal tubing, usually annular in cross-section, which are welded, bolted or otherwise connected. It will be evident that such members may be readily provided with eyes or loops, as previously described and as generally shown in Fi re 7. On the other hand, where special s apes are employed for the frame members, provision may be made for the formation of the eyes or loops to which the fabric skin of the fuselage may be tied in any of the ways heretofore described. The same applies to the building or fabricating of other structures wherein it is desired to attach a cloth or similar covering to metallic frame elements, the feasibilit of incorporatin the loops or eyes in tu ular or other mem ers of any cross-section or shape being obvious.

From the foregoing, it will be seen that I have provided a simple, economical and highly efficient method of constructing various structural components of metal and fabric, and onewhich materially advances the field of usefulness of such composite constructions.

I claim:

1. A rib for use in airplane wing construction embodying integral rolled top and bottom edges having depressions and cooperating raised surfaces located at' intervals from end to end of said edges to provide meansthrou h which a flexible tying element for anc oring a fabric coverin to said rib, may be passed longitudinally o the rib.

2. A rib for airplane wing construction formed from sheet metal, having integral tube-like top and bottom edges, means having opposed curved surfaces located at intervals along said top and bottom edges of the rib to permit of the passage of a tyin elementtherethrough between said oppose surfaces, wherebv a wing covering may be fixed to the rib and spar seats positioned fore and aft in the web of said rib, said seats being integral with said web.

3. As a new article of manufacture, an airlane wing rib stamped from sheet metal and iiaving its upper and lower edges rolled in a tube-like configuration, such upper and lower edges having depressions spaced along the cover-supporting surfaces thereof adapted to cooperate with sections of the walls ofsaid edges to form loops through which a covering securing element may be assed to anchor a covering material to said ri 4. A metal frame member to be used in conjunction with a fabric covering, having depressions formed at intervals along the coversupporting surface thereof, adapted to cooperate with adjacent sections of said surface to form loops through which flexible coverfastening means may be threaded.

5. A rib for airplane construction produced from a single sheet of metal, the longitudinal edges of said rib having a. tubular cross-section, portions of the outer surface of each rolled edge being depressed, the respective depressions being bi-sected by a raised strap connecting the opposite walls thereof, each strap having a centrally located dependent shoulder, said depressions and straps cooperating to form means for the reception of a longitudinally disposed covering tying element.

6. A means of attaching fabric covering to a metallic frame element in airplane con struction, comprising cooperating surfaces integral with said element adapted to receive and retain a flexible fabric tying medium, said surfaces including a depression merging into the body of said element, a relatively narrow strap raised from the depressed surface and lying transversely thereof intermediate of its ends, and a shoulder having a curved surface dependent from said strap.

7. A rib for an airfoil formed from a single sheet of metal, the top and bottom edges thereof being rolled in opposite directions relative to the web, and provided with relatively spaced integral depressed and raised curved surfaces cooperating to form retain ing means for fabric lacin disposed longitudinally of the rib, and ore and aft spar seats formed by openings in the web and flanges integral with the web and surrounding said openings.

8. A retainer for fabric lacing in connecting fabric to metallic frame members in airplane construction, comprising a depression in the face of the fabric-supporting frame member, an integral strip of metal disposed transversely of said depression and spaced therefrom and a curved surface shoulder rojecting from the said strip toward the ass of the depression, the peak of said shoulder lying substantially in the plane of the face of the frame member at either end of the de presslon.

9. A rib for airfoils formed from a single blank of metal, having a substantially unbroken web portion, with top and bottom flanges of an annular cross-section, said flanges being produced by rolling the u per edge of the blank in one direction toward the we the lower edge of the blank being rolled in the opposite direction, each of said flanges having depressions at intervals along their covering-supporting surfaces and integral metallic strips spanning said depressions to form eyelets through which aflexible wingcovering fastening-medium may be threaded. the inner face of each of said strips having a curved protuberance, said rotuberanoes: and the contour of the depressions functioning to eliminate detrimental friction between the eyelets and the covering fastening me dium.

10. A means for anchoring a covering material to a metallic frame member by utilizing a continuous flexible element in engagement with the covering material and said frame member, comprising an eyelet, in said frame member, produced b the formation of a depression, with curve connecting sur faces, therein, spanning the depression intermediate its ends by a stri of metal raised above the plane of the b0 y of the frame member and expanding a portion of the strip inwardly to form a curved surface protuberance directed toward the base of the depression, the curved surfaces definin the depression and the curved surface of t e rotuberance being ada ted to form the media of contact between t e fastening element and the eyelet.

ANTHONY H. G. FOKKER.

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